We are studying the role of cellular endoplasmic reticular (ER) membranes in the replication and morphogenesis of poliovirus. In specific, we are attempting to determine the interrelationship between viral RNA synthesis, which occurs on smooth ER membranes, and viral protein synthesis and assembly of empty capsids, which occur on rough ER membranes. In addition, temperature-sensitive mutants have been isolated and will be used to further explore the nature of different virus-specific particles and their role in virus assembly. BIBLIOGRAPHIC REFERENCES: Mina Perlin and Bruce A. Phillips. 1975. In vitro Assembly of Polioviruses. IV. Evidence for the existence of two assembly steps in the formation of empty capsids from S14 particles. Virology 63, 505-511.